Construction and Expression of Tp0453 Recombinant Protein of Treponema pallidum and Development of Indirect ELISA for Diagnosinq Syphilis

Objectives： To clone and express Tp0453 outer membrane protein of Treponema pallidum, and to evaluate its significance in the serodiagnosis of syphilis. Methods： The immuno-dominant epitope of Tp0453 gene was amplified from the complete genome of T.pallidum by polymerase chain reactions （PCR）, subcloned into the expression vector Pqe32 to generate recombinant plasmid Pqe32/Tp0453, and was then expressed in E. coli M15. The fusion protein was purified with Ni-NTA affinity purification. Indirect ELISA was developed to detect human serum IgG antibody to T. pallidum. Results： The recombinant Tp0453 protein was successfully expressed and purified. The recombinant protein had a molecular weight of approximately 32KDa.Indirect ELISA to the recombinant protein was developed.Sixty control sera were tested by ELISA and yielded a sensitivity of 100% （30/30） and a specificity of 100% （30/30）. While testing for T. pallidum in human sera, the sensitivity and specificity of ELISA were 96.8% and 100%, respectively, when compared with TPPA test results. The concordance of results between the ELISA test and the TPPA test was 98.2%. Conclusion： The recombinant Tp0453 outer membrane protein elicited a strong immunoreaction to anti-T.pallidum IgG antibody and has great potential use in ELISA for the serodiagnosis of syphilis.

Recombinant human zona pellucida proteins ZP1, ZP2 and ZP3 co-expressed in a human cell line

Aim: To produce biologically active recombinant human (rh) ZP proteins in a human cell for use in sperm function tests. Methods: The human embryonic kidney cell line 293T was employed to produce rhZP1, rhZP2 and rhZP3 proteins individually and together by co-expression. Presence of these proteins in the culture medium and cell lysate was assessed by Western blotting analysis. The effect of the recombinant proteins on the human AR was assessed. Results: RhZP2 and rhZP3 were secreted into the culture medium, whereas rhZPl was found only in the cell lysate. Interestingly, when all zona pellucida proteins were co-expressed in the same cells, rhZPl was also secreted into the culture medium. However, despite the presence of all three ZP proteins in sufficient concentration and evidence of heavy glycosylation on gel electrophoresis, biological activity to induce the AR was not observed. Conclusion: RhZP1, rhZP2 and rhZP3 were successfully expressed in the human embryonic kidney cell line 293T. It appears that an interaction amongst these proteins may be required for release of rhZPl from the cell. Although this approach is not satisfactory for producing active human ZP proteins, it makes a significant contribution to the understanding of the structural and functional characteristics of the ZP proteins.

Immunogenicity and protective efficacy of recombinant M2e.Hsp70c(Hsp70_(359–610)) fusion protein against influenza virus infection in mice

New strategies in vaccine development are urgently needed to combat emerging influenza viruses and to reduce the risk of pandemic disease surfacing. Being conserved, the M2 e protein, is a potential candidate for universal vaccine development against influenza A viruses. Mycobacterium tuberculosis Hsp70(mHsp70) is known to cultivate the function of immunogenic antigen-presenting cells, stimulate a strong cytotoxic T lymphocyte(CTL) response, and stop the induction of tolerance. Thus, in this study, a recombinant protein from the extracellular domain of influenza A virus matrix protein 2(M2e), was fused to the C-terminus of Mycobacterium tuberculosis Hsp70(Hsp70c), to generate a vaccine candidate. Humoral immune responses, IFN-γ-producing lymphocyte, and strong CTL activity were all induced to confirm the immunogenicity of M2 e.Hsp70c(Hsp70359–610). And challenge tests showed protection against H1N1 and H9N2 strains in vaccinated groups. Finally these results demonstrates M2 e.Hsp70c fusion protein can be a candidate for a universal influenza A vaccine.

Green Fluorescent Protein Recombinant Nisin as a Probe for Detection of Gram-Positive Bacteria

A great amount of foodborne pathogens were Gram-positive (G+) bacteria, a threat to public health. In this study, considering the binding ability of nisin towards G+ bacteria and the stable fluorescent ability of EGFP protein, a fluorescent nisin–EGFP protein probe was constructed by a gene engineering method. Nisin and EGFP were used as the receptor and fluorophore, respectively, to detect G+ bacteria. The nisin and egfp gene were amplified separately according to the sequence published in GenBank using unique primers. The two genes were cloned into a pET-28b(+) vector resulting in a pET-28b(+)–nisin–egfp vector. The vector was transferred into Escherichia coli (E. coli) BL21 (DE3) for expression. The expressed protein was extracted, purified by a Ni–NTA column, and then tested by the SDS-PAGE method to confirm its molecular weight. Listeria monocytogenes (L. monocytogenes), Staphylococcus aureus (S. aureus), and Micrococcus luteus (M. luteus) were used as the representations of G+ bacteria. E. coli O157, representing the gram-negative (G−) bacteria, was used as a negative control. The binding specificity of the recombinant protein was performed on two types of bacteria and then detected through fluorescent microscopy. The results indicated that the nisin–EGFP probe could detect G+ bacteria at 108CFU/mL. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

Susceptibility to AcMNPV and Expression of Recombinant Proteins by a Novel Cell Clone Derived from a Trichoplusia ni QAU-BTI-Tn9-4s Cell Line

It is well known that Tn5B1-4 (commercially known as the High Five) cell line is highly susceptible to baculovirus and provides superior production of recombinant proteins when compared to other insect cell lines.But the characteristics of the cell line do not always remain stable and may change upon continuous passage.Recently an alphanodavirus,named Tn5 Cell Line Virus (or TNCL Virus),was identified in High Five cells in particular.Therefore,we established a new cell line,QB-Tn9-4s,from Trichoplusia ni,which was determined to be free of TNCL virus by RT-PCR analysis.In this paper,we describe the development of a novel cell clone,QB-CL-B,from a low passage QB-Tn9-4s cell line and report its susceptibility to AcMNPV,and the level of recombinant protein production.This cell clone was similar to its parental cells QB-Tn9-4s and Tn5B1-4 cells in morphology and growth rate;although it also showed approximately the same responses to AcMNPV infection and production of occlusion bodies,there were higher levels of recombinant protein production in comparison to QB-Tn9-4s (parental cells) and High5 cells.

Expression of fluorescent tagged recombinant erythroferrone protein

Objective: To produce fluorescent tagged recombinant erythroferrone protein(ERFE_eGFP) for laboratory investigations. Methods: Erythroferrone(ERFE) gene was fused to green fluorescent protein(eGFP) gene and cloned in a pSecTag2Hygro plasmid. The constructed plasmid was amplified in Escherichia coli DH5α and the eGFP-fused ERFE(ERFE_eGFP) protein was expressed in human embryonic kidney(HEK293T) cell line. Results: The plasmid constructed from colony C6 contained ERFE_eGFP with the correct restriction sizes of 4.2 kb and expressed secretory ERFE_eGFP fusion protein(approximately size of 75 kDa) in HEK293T cell line. Conclusions: ERFE_eGFP recombinant protein is successfully expressed as a secretory functional protein and could be sensitively detected using fluorometry. This fusion protein might benefit future applications for localization of cellular ERFE receptors and competitive immunoassay of ERFE concentration.

Active Peptides and Motifs within Collagen and Other ECM Proteins

Collagens are the most abundant proteins in mammals and form an extracellular matrix (ECM) with other components as the structural support of muscle, skin, corneas and blood vessels etc. Other than providing structural support, the ECM exhibits active communication with cells and influences many cellular processes including migration, wound healing, differentiation and cancer metastasis. Though collagen proteins contain highly repetitive primary sequences and defined tertiary structures, more and more studies have shown that many short peptides/motifs within collagen proteins play key roles in various biological processes. These short sequences are effective within triple helical structures or independently as stand-alone molecules resulting from proteolytic degradation. Besides endogenous ECM-derived peptides, many more functional peptides have been produced by tissue processing, chemical synthesis, and recombinant protein production. In this review, we summarize different peptides/motifs identified in collagen and other ECM proteins and discuss their potential for medical, personal care, and cosmetics applications.

Induction of Chondrogenesis of Adipose-derived Stem Cells by Novel Recombinant TGF-β3 Fusion Protein

Summary： A new type of TGF-β3 fusion protein with targeted therapy function was constructed, and its feasibility and target specificity of inducing chondrogenesis were investigated by transfecting LAP-MMP-mTGF-β3 gene into adipose-derived stem cells （ADSCs）. The recombinant pIRES- EGFP-MMP was constructed by inserting the sense and antisense DNA of encoding the amino acid of the synthetic MMP enzyme cutting site into the eukaryotic expression vector pIRES-EGFE LAP and mTGF-β3 fragments were obtained by using RT-PCR and inserted into the upstream and downstream of MMP from pIRES-EGFP-MMP respectively, and the recombinant plasmid of pIRES-EGFP- LAP-MMP-mTGF-β3 was constructed, which was transferred to ADSCs. The ADSCs were cultured and divided in three groups： experimental group （MMP group）, negative control group （no MMP） and non-transfection group. The morphological changes were observed microscopically, and the expression of proteoglycan and type II collagen （Col II） was detected by using Alcian blue staining and immuno- histochemistry staining at 7th, 14th and 21st day after culture. The recombinant plasmid of pIRES-EGFP-LAP-MMP-mTGF-β3 was correctly constructed by methods of enzyme cutting and se- quencing analysis. The mTGF-β3 fusion protein was successfully expressed after transfection, and in the presence of the MMP, active protein mTGF-β3 was generated, which significantly promoted differ- entiation of ADSCs into chondrocytes and the expression of cartilage matrix. The novel fusion protein LAP-MMP-mTGF-β3 can targetedly induce differentiation of ADSCs into chondrocytes, which would open up prospects for target therapy of cartilage damage repair in future.

Rat recombinant β-defensin 22 is a heparin-binding protein with antimicrobial activity

Approximately 40-50 β-defensins are predominantly expressed in the male reproductive system of mammals. This selective expression raises the question as to the roles of these molecules in innate immunity and fertility in the male reproductive tract. Rat β-defensin 22 is an epididymis-specific β-defensin expressed in segments 12-14 of the epididymis. This protein contains both β-defensin and lectin signature sequences, yet its antimicrobial activity and carbohydrate-binding ability have not been shown. We herein demonstrated the antimicrobial activity of recombinant rat β-defensin 22 against Escherichia coliand Candida albicans. Its lectinJike activity was also investigated by demonstrating its binding ability with heparin beads. This heparin-binding activity implies some potential roles for this defensin in determining the fertilisation capabilities of sperm.

Recombinant human bone morphogenetic protein-7 expressed from CHO cells possessing the activity of bone-induced in vitro

Objective To express the recombinant human bone morphogenetic protein-7 (rhBMP-7) in Chinese hamster ovary (CHO) cells and to establish the in vitro biological activity assay of rhBMP-7. Methods Human BMP-7 cDNA was subcloned into pcDNA3.1 mammalian expression vector and transfected to CHO cells by using the lipofectin transfection method. BMP-7 expression cell culture supernatants were harvested and purified for target protein. To analyze the bioactivity of the secreted rhBMP-7, a novel in vitro assay was established by measuring its alkaline phosphatase (ALP) stimulating of osteoblast cell line, W-20-17. Results BMP-7 stably expressing cell clone was selected, which secreted mature disulfide-linked homodimer form of hBMP-7 and had an apparent molecular weight of 36kDa. rhBMP-7 with >95% purity was obtained using 3 step chromatography method. Bioactivity assay showed that the purified protein specifically stimulated W-20-17 cell producing ALP, with a 4-fold increase of ALP activity at 100ng/ml or more, and the EC50 of 15.6ng/ml. Conclusion Purified rhBMP-7 from this CHO expression system has significant biological activity in induction of osteoblast phenotype, which demonstrates potential bone regeneration activity.

Expression and purification of the recombinant outermembrane protein Tp0453 of Treponema pallidum and its characterization of immuno-competence

To clone and express the recombinant outer membrane protein Tp0453 of Treponema pallidum and to analyze the immuno-reactivity and immunogenicity of the expressed protein, the immuno-dominant epitope of the Tp0453 was amplified from the complete genome of T.pallidum by PCR, subcloned into expression vector pQE32 to generate the recombinant plasmid pQE32/Tp0453, then expressed in E.coli M15 and analyzed by SDS/PAGE and Western blotting. The fusion protein expressed was purified with Ni-NTA affinity chromatography. Its immuno-reactivity was assayed by indirect ELISA, and the immunogenicity was determined by immunization with this fusion protein in New Zealand rabbits. In the present study, a fusion protein of molecular weight about 32 kDa was obtained. As demonstrated by Western blotting, the recombinant protein could react specifically with positive IgG sera of patients with syphilis, and the antibodies against T.pallidum in human sera were successfully detected by indirect ELISA. Both the sensitivity and specificity of ELISA based on the Tp0453 fusion protein as were 100% (30/30) when detected with control sera. In comparison with the results of IgG ELISA with those of TPPA. It was found that the sensitivity of ELISA was 96.8% and the specificity was 100%. The difference of ELISA and TPPA was not significant, and the concordance of results between ELISA and TPPA was 98.2%. In addition, specific humoral responses could be elicited by immunization with the recombinant fusion protein in New Zealand rabbits with a specific antibody titer of 1∶1280 after 3 successive doses of immunization. These results demonstrate that the expressed recombinant fusion protein shows excellent immuno-competence and provide foundation to develop a quick diagnostic kid applied to detect the presence of T.pallidum infections.

Gene cloning and prokaryotic expression of recombinant outer membrane protein from Vibrio parahaemolyticus

Gram-negative Vibrio parahaemolyticus is a common pathogen in humans and marine animals, The outer membrane protein of bacteria plays an important role in the infection and pathogenicity to the host. Thus, the outer membrane proteins are an ideal target for vaccines. We amplified a complete outer membrane protein gene （ompW） from E parahaemolyticus ATCC 17802. We then cloned and expressed the gene into Escherichia coli BL21 （DE3） cells. The gene coded for a protein that was 42.78 kDa. We purified the protein using Ni-NTA affinity chromatography and Anti-His antibody Western blotting, respectively. Our results provide a basis for future application of the OmpW protein as a vaccine candidate against infection by E parahaemolyticus. In addition, the purified OmpW protein can be used for further functional and structural studies.

Evaluation of Six Recombinant Proteins for Serological Diagnosis of Lyme Borreliosis in China

Objective In this study, we evaluated the diagnostic efficiency of six recombinant proteins for the serodiagnosis of Lyme borreliosis （LB） and screened out the appropriate antigens to support the production of a Chinese clinical ELISA （enzyme-linked immunosorbent assay） kit for LB. Methods Six recombinant antigens, Fla B.g, OspC B.a, OspC B.g, P39 B.g, P83 B.g, and VlsE B.a, were used for ELISA to detect serum antibodies in LB, syphilis, and healthy controls. The ELISA results were used to generate receiver operating characteristic （ROC） curves, and the sensitivity and specificity of each protein was evaluated. All recombinant proteins were evaluated and screened by using logistic regression models. Results Two IgG （VISE and OspC B.g） and two IgM （OspC B.g and OspC B.a） antigens were left by the logistic regression model screened. VIsE had the highest specificity for syphilis samples in the IgG test （87.7%, P〈0.05）. OspC B.g had the highest diagnostic value in the IgM test （AUC=0.871）. Interactive effects between OspC B.a and Fla B.g could reduce the specificity of the ELISA. Conclusion Three recombinant antigens, OspC B.g, OspC B.a, and VisE B.a, were useful for ELISAs of LB. Additionally, the interaction between OspC B.a and Fla B.g should be examined in future research.

Preparation and analysis of immunocompetence of recombinant fusion protein of the immunodominant region in chlamydial protease-like activity factor from Chlamydophila pneumoniae and its application in serodiagnosis

To clone the gene coding the immunodominant region in the chlamydial protease-like activity factor （CPAF） from Chlaroydophila pneumoniae, to analyze immunoeoropetenee of the expressed protein, and to evaluate its value in serodiagnosis, the CPAF immunodominant region gene was amplified, ligated into a pGEX6p-2 vector, and then the expressed recombinant protein was purified with glutathione Stransferase （GST） agarose gel FF after renaturation, then identified by SDS-PAGE and Western blot. A new indirect ELISA was developed with the purified protein as coating antigen. The immunogenicity of the recombinant protein was evaluated by immunization to New Zealand rabbits, and its immunoreactivity was analyzed by reacting with anti-C, pneumoniae antibody. 300 clinical sera samples were respectively detected by mieroimmunofluorescenee （MIF） as reference method and the indirect ELISA, and the difference between the two methods was analyzed. Cross-reactivity against Chlamydia trachomatis was investigated with the indirect ELISA to detect anti-C, trachomatis positive antisera. The results indicated that a 51.3 kDa recombinant protein was obtained. Western blot assay proved that the recombinant protein could merely specifically react with human anti- C. pneurnoniae antisera. The titers of the specific IgG antibodies in the immunized New Zealand rabbits were above 1 ： 16 000. Anti- C. pneumoniae IgG positive and negative reference sera were detected with the indirect ELISA, and the concordance rate of negative and positive results were both 100% （40/40）. The sensitivity and specificity of the indirect ELISA in comparison with MIF were 93.8% （45/48） and 100% （252/252） separately by detecting 300 clinical sera samples, and the concordance rate between the two methods was 99.0%. No cross reaction against C. trachomatis was found with the indirect ELISA to detect anti-C, trachomatis positive antisera. In conclusion, the prepared recombinant protein of the CPAF immunodominant region shows excellent immunocompetence and can be used to develop a new indirect ELISA as a method to detect anti-C, pneumoniae antibody for diagnosis of C. pneumoniae infection.

Detection of Antibodies against Toxoplasma gondii by ELISA with Recombinant Microneme Protein 3

[Objective] To develop a new method for serodiagnosis of swine toxoplasmosis. [Method] With the purified recombinant microneme protein 3 （rMIC3） as coating antigens, an indirect ELISA was developed for detection of antibodies against Toxoplasma gondii. [ Result] The optimal working concentration of rMIC3 was 3. 40 ug/ml, and the optimal degree of dilution of sera was 1：160. Cross-reaction was not observed between the Toxoplasma gondii-positive sera and the positive sera against classical swine fever virus or some other pathogens. The developed ELISA had 92.56% coincidence rate with latex agglutination test. [ Conclusion] The developed ELISA is sensitive, rapid, specific and reproducible, and thus it can be applied in serodiagnosis and seroprevalence investigation of swine toxoplasmosis.

Safety of Human Recombinant Proteins

Recombinant human proteins play an important role in therapy, especially in stimulating the hematopoiesis after chemotherapy, e. g., erythropoietin and colony stimulating factors,while several promising candidates such as IL-6, IL-12, thrombopoietin and others are in clinical development. Since the recombinant proteins are copies of endogenous proteins, it was assumed that they would be well tolerated. While this assumption is correct for some, other proteins proved to be less well tolerated. Therefore, preclinical safety assessment of these pro teins is necessary. Based on the experience with several proteins, some guidance for the safety assessment can be given. Furthermore, data are presented demonstrating that preclinical toxi city studies may have a predictive value for man. Limitations of the classical approach of safety tests and new concepts are discussed

CORAL AS A CARRIER FOR RECOMBINANT HUMAN BONE MORPHOGENETIC PROTEIN-2

By combining coral with recombinant human bone morphogenetic protein-2 (rhBMP-2), rhBMP-2/coral composite was obtained in this study. Following implantation of the composite into the muscle pouches of mice, cartilage growth was induced in the pores or on the surface of the implants at one week, woven bone at three week and lamellar bone with bone marrow at six week, and coral was absorbed partially. The induced formation of endochondral bone was time-related and rhBMP-2 dose-related. The results of this study indicate that the composite possesses a superior ability of osteogenesis, and coral acts as one of the most suitable rhBMP-2 slowrelease carriers currently available. The composite will be a new type of bone substitute to be used in orthopaedics and maxillofacial surgery.

Cloning and expression of human arresten gene and effect of its recombinant protein on endothelial cell proliferation

To clone human arresten gene and investigate biological activity of the recombinant protein.Methods Human arresten gene was obtained from the plasmid pGEMArr and subcloned into the BamHⅠ and Pst Ⅰ restriction sites of prokaryotic expression vector pRSET containing T7 promoter.The recombinant plasmid pRSETAN was subsequently transformed into the strain E.coli BL21(DE3),and the target gene was expressed under induction of IPTG.The expressed protein was extracted,purified by Ni 2+ chelation affinity chromatography and refoled.The effect of the recombinant protein on proliferation of human umbilical vein endothelial cells (HUVECs) was also analyzed with the MTT assay.Results Endonuclease digesting and DNA sequencing confirmed that the arresten gene was correctly inserted into the expression vector.The recombinant protein was hightly expressed in the form of inclusion body in the host bacteria after induction.SDS-PAGE analysis revealed that the recombinant protein with a molecular weight of 26×103 amounted to 27% of the total bacterial proteins.The purity of the expected protein could reach over 96% through affinity chromatography.After renaturation,the recombinant protein could reach over 96% through affinity chromatography.After renaturation,the recombinant protein could significantly suppress proliferation of human umbilical vein endothelia cells(HUVECs) induced by vascular endothelial growth factor(VEGF).Conclusion Human arresten gene was successfully cloned into the expression vector pRSET and expressed at high level in Escherichia coli.Purified and refolded arresten protein could effectively inhibit proliferation of vascular endothelia cells.2 refs.

Preparation of Monoclonal Antibody against P65 Protein of Mycoplasma hyopneumoniae

P65 protein, the major immunodominant protein of Mycoplasma hyopneu-moniae （Mhp） exhibiting no cross-reaction with other mycoplasmas, is general y used as a target protein for Mhp detection. In this study, BALB/c mice were immunized with prokaryotical y expressed P65 recombinant protein to prepare monoclonal anti-body. After screening with Mhp whole-cel protein and P65 protein, a specific hy-bridoma cel line, 3G12, was obtained by ELISA. Identification results indicated that the antibody secreted by 3G12 hybridoma cel s could react with P65 protein and Mhp whole-cel protein. According to indirect ELISA assay, 3G12 cel culture super-natant possessed a titer of 1∶12 800 against P65 protein and 1∶3 200 against Mhp whole-cel protein; 3G12 ascites possessed a titer of above 1∶4 000 000 against P65 protein and above 1∶20 000 against Mhp 168 whole-cel protein. After long-term in vitro culture and continuous freezing-thawing, 3G12 cel line could stably secrete antibodies. A monoclonal antibody against P65 protein and Mhp whole-cel protein was successful y obtained in the present study, which provided basis for further in-vestigating the pathogenic mechanism of Mhp and establishing diagnostic methods of Mycoplasmal pneumonia of swine （MPS）.